1. Technical Field
The present invention generally relates to automated data analysis. More particularly, the present invention relates to automated analysis of sensed data representative of gaseous species present in a plasma.
2. Background Art
For most plasma processes, data obtained regarding the gaseous species present in the plasma at any given time must be analyzed off line by an analyst trained to analyze such data. The off-line analysis of such data is important for plasma process control, among other things. However, the analysis of such data has proven to be a difficult and time-consuming process for such analysts.
Certain techniques have been demonstrated as potential monitors of gaseous species in a plasma process. These techniques include Optical Emission Spectroscopy (OES), Fourier Transform Infra-red Spectroscopy, and Laser Induced Fluorescence. Each technique offers unique information about a plasma environment. However, each of these analytical approaches characterizes gaseous species by determining an intensity for one or more electromagnetic wavelengths occurring at the same point in time within the plasma environment.
In the preferred embodiment described herein, an optical emission spectrometer is utilized as the sensor of choice. An optical emission spectrometer is a commercially available device used to detect the presence and relative concentrations of various gases in a plasma chamber. The optical emission spectrometer works by detecting light emitted from within the chamber, both the relative intensity thereof and the corresponding wavelength.
The process of analyzing data relating to the gaseous species in a plasma is historically a manual one. However, in recent years limited progress has been made with respect to partially automating the analysis. For example, some automated systems hold known intensity and wavelength data for particular gases and assist in manual calibration of the raw data. None of the existing systems have fully utilized the available computer technology to speed the analysis and increase the accuracy of the results.
Thus, a need exists for more extensive automated assistance in interpreting data obtained from a plasma process regarding gaseous species therein.